Your router normally function by doing Network Address Translation, meaning that you have an IP network on your side of the the router that is separate from the IP network on the Internet side of the router. In this mode, the router has two IP addresses and can normally be managed by a web browser using the internal IP address. In bridge mode, the router will bridge your network with the one that it is directly connected to on it's Internet port. It will use a MAC address table to filter out packets that are destined for other customer's routers so you don't flood your network with packets that are useless to you. In this mode, it doesn't look at the IP portion of any packet and has no IP address of its own. To you, it looks like all of your devices are directly connected to the ISPs network. Since it doesn't have an IP, you can't point a web browser at it, and therefore you can't manage it.

This doesn't mean it doesn't work. A router in bridge mode needs no configuration. In order to get it back to NAT mode, just push the factory reset button and configure it how you want it. Most people who use bridge mode do it precisely because they don't want to manage it. For example, a more sophisticated user might have their own security device and all they want from the ISPs equipment is to move packets. Instead of trying to get a DSL or cable connection on the security device, it's cheaper and way less hassle to just take what the ISP gives you and put it into bridge mode.

and it was so Experimental copies did work with another set of database tables and if those tables was not propery set, the program could not work.Normally changes in this tables was NOT transmited along other changes, as only experimental copies used them. So switching this switch without futher action resulted nearly inevitably to broken data set and not working program. And users was not supposed to do so.

Was I the only guy who thought about poor Hayes emulation implementation in modems (the ones that modulate/demodulate via a phone line, not DSL or any other modern stuff) that could be made to disconnect by visiting a link like http://www.google.de/?q=+++ATH (while the software still thought them to be connected and in some cases it was even impossible to re-dial without resetting the modem or restarting the computer)? But presumably, these days are over now

I remember 16 years or so ago AOL did something to the 33.6 modem in my Windows 95 computer that prevented it from connecting with regular ISPs after I had uninstalled AOL. Wasn't particularly computer savvy back then, and obviously couldn't look up anything online (at least at home), so I had to just backup (all my school docs could fit on two floppies) and restore

That button turns your modem/router into just a modem. You can't manage a modem since it doesn't have an IP address. It's the button you want to hit if you want to use a different device as your router and don't want the aggravation of two routers in the same LAN.

Yeah, as others here have already said, this disables everything on the device except for the modem and passes all traffic transparently, so you can put your own router/firewall (one without a modem) 'behind' it. This is a very useful feature, and one I often look for in an ADSL 'router', so I can use my own (non shitty) router instead, so I can use things like, oh, site-to-siteI PSEC VPNs or an IPv6 tunnel.

What is unusual here is that this renders the device unmanageable. Every broadband modem/router I've ever used that supported bridge mode allows device management by still configuring a LAN interface with an IP, which you can do without interfering with the transparent bridge.

This bit's always confused me. Back in the days of dialup, my modem would receive an external-facing IP address.

I've spoken to those in USA that have a separate modem and router but in UK ADSL kit usually has both modem and router in one box. The admin screen shows the LAN IP address of the router and the external IP address of the modem - unless that's wrongly-labelled and the modem is purely responsible for creating the connection then passing off the IP association part to the router.

This bit's always confused me. Back in the days of dialup, my modem would receive an external-facing IP address.

Not really - your computer received an external-facing IP address. The modem just allowed your computer to connect a serial link to phoneline.@Cassidy said:

I've spoken to those in USA that have a separate modem and router but in UK ADSL kit usually has both modem and router in one box.

This usually depends on the ISP and age of the modem - around here (in Slovenia) old ADSL modems were just modems, and the computer needed to establish PPPoE connection (or just plain ethernet connection, again depending on ISP). Newer ones can also work as routers and sometimes have VoIP to PSTN adapters and wireless built-in.

This usually depends on the ISP and age of the modem - around here (in Slovenia) old ADSL modems were just modems, and the computer needed to establish PPPoE connection (or just plain ethernet connection, again depending on ISP). Newer ones can also work as routers and sometimes have VoIP to PSTN adapters and wireless built-in.

Yeah, where "old" is circa 2001. The original Alcatel speed touch home was a modem only, though the "pro" version had a router (one could hack the home version into a pro with the caveat there was no way to secure it). We used one with a linux PC "router" for several years. I've had a modem router since 2004 (Billion 5100, replaced with a 7404VGPM in 2008 to get ADSL2+ access). My new Billion has VoIP, wireless, VPN and annex M access. It can apparently be hacked to use one of the LAN ports as an Ethernet wan, which I'll probably have to use if I can't afford a new router when/if the NBN arrives (which is gig-Ethernet based)